A novel 92kDa type IV collagen degrading enzyme was observed to be associated with the malignant phenotype. This enzyme was semipurified by two different procedures and its activity was compared to that of 67kDa gelatinase/type IV collagenase. Both enzymes exhibited similar substrate specificities degrading human placental type IV collagen, human type III collagen, bovine type 1 collagen, and gelatin. Both enzymes exhibited a similar size reduction following incubation with the organic mercurial compound APMA, a substance reported to activate collagenases. Both enzymes were released in a latent form from cells in culture. However, true activators of these enzymes remain to be elucidated. Purified 92kDa enzyme obtained from HL60 cell culture supernatant was found to be N terminal blocked during protein sequence analysis. Studies are underway to obtain protein sequence data from APMA generated fragments of the enzyme. Polyclonal antibodies against the 92kDa enzyme are presently being generated. Once protein sequence data and antibodies are obtained it is proposed to obtain cDNA clones encoding the 92kDa enzyme. Other cDNA clones isolated in this group include type 1 collagenase, 67 kDa type IV collagenase and tissue inhibitor of metalloproteinases (TIMP). These clones will be used to further study the relative importance of these metalloproteinases and their inhibitor in both tumor invasion and metastasis in vivo and tumor cell interactions with endothelial cells in vitro.